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| last update: 02.11.10 |
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| What´s
a BAC array? |
What´s
array CGH? |
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Each spot on a Bacterial Artificial Chromosome array represents the
very specific part
of the genome that is contained in the BAC. A whole genome tiling path
BAC
array comprises as many BAC clones as necessary to cover the whole
genome in an
overlapping manner (~32400 for the human genome). The upper part of the
image
is based on a screenshot of the UCSC Human Genome Browser. The red
lines
illustrate the selection of overlapping clones out of a comprehensive
BAC
library. The array used in our lab is based on the human 32k Re-Array set (http://bacpac.chori.org/pHumanMinSet.htm; DNA kindly provided by Pieter de Jong (Krzywinski, et al., 2004; Osoegawa, et al., 2001; Ishkanian, et al., 2004), the 1Mb Sanger set (clones kindly provided by Nigel Carter, Wellcome Trust Sanger Centre)(Fiegler, et al., 2003) and a set of 390 subtelomeric clones (assembled by members of the COST B19 initiative: Molecular Cytogenetics of solid tumors). |
Array CGH is a molecular cytogenetic method for the detection of chromosomal gains and losses. The technique is based on the co-hybridization of differentially labelled test and reference DNA onto an array of DNA spots printed on a glass slide (e.g. a BAC array). In case of a deletion in the test DNA, less test DNA will bind to the corresponding spots and the red label of the reference DNA will prevail; gains in the test genome can be identified by a dominance of the green label of the test DNA. Spots, representing sequences with the same copy number in the test genome relative to the reference genome appear yellow. For BAC arrays, an excess of repetitive Cot DNA has to be added in order to suppress otherwise unspecifically binding repetitive sequences. Using our array CGH platform, we have been able to detect heterozygous deletion as small as 80kb.
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